Think Twice About That Pet Cat

By Frederik Joelving

Sure, they're cute, and can be good for your kid, but purchasing a cat in adulthood nearly doubles your chances of developing an allergic reaction to them, according to a new study.

Tempted by the playful antics of that adorable kitten in the pet shop? If you've never had a cat before you may want to think again, especially if you have other allergies, researchers warn. And if you do acquire a feline, keep it out of your bedroom.

While having a cat as a child may protect against future allergies, getting one in adulthood nearly doubles the chances of developing an immune reaction to it -- the first step toward wheezing, sneezing, and itchy eyes, a European study found.

The same study, which covered thousands of adults and was published in The Journal of Allergy and Clinical Immunology, found that people with other allergies were at extra high risk of reacting to a new feline in the house.

"Our data support that acquiring a cat in adulthood nearly doubles the risk of developing cat sensitization."

"Our data support that acquiring a cat in adulthood nearly doubles the risk of developing cat sensitization," wrote Mario Olivieri, from the University Hospital of Verona in Italy. "Hence, cat avoidance should be considered in adults, especially in those sensitized to other allergens and reporting a history of allergic diseases."

For the study, researchers surveyed more than 6,000 adult Europeans twice over nine years, taking blood samples. None of the participants had antibodies to cats in their blood to start with, meaning they were not sensitized to the animal's dander. Sensitization can be measured in a skin prick test. It does not necessarily lead to symptoms, but in many cases it is the harbinger of full-blown allergies.

About three percent of people who did not have a cat at either time of the survey became sensitized over the course of the study, compared to five percent of those who acquired a cat during those nine years. Four in 10 of the newly sensitized also said they experienced allergy symptoms around animals, four times the rate seen among people without antibodies against cats.

It also turned out that only people who let their pet into the bedroom became sensitized. "If you are an adult with asthma and/or allergies, you should think twice about getting a cat and particularly, if you do so, letting it into your bedroom," said Andy Nish of the Allergy and Asthma Care Center in Gainesville, Georgia, who wasn't involved in the study.

The researchers did find, however, that people who had had a cat in childhood had a much smaller risk against becoming sensitized to it than those who were new cat owners. "We thought that having a cat in early childhood may be protective against the development of cat allergy in childhood, but this study seems to indicate that protection extends into adulthood," Nish told Reuters Health in an email.

Noting that he always recommends keeping cats out of the bedroom, he added: "It is remarkable that none who did not allow the cat in the bedroom became sensitized."

For people who have a cat and have become allergic, he recommended finding a new home for the pet, followed by keeping the cat outdoors at all times. "If it comes in even occasionally, its dander will remain in the house for months. If the cat needs to be indoors, at least keep it out of your bedroom, consider a HEPA filter for your bedroom, and consider washing the cat at least once a week," he added.